With the development of communications technology, an electronic device such as a smartphone has an increasing demand for having the multi-antenna and the multi-frequency band, and the electronic device also needs a more compact structure. Due to some structural and industrial design limitations, it is difficult for an electronic device to be freely designed entirely based on the requirement for antenna. Therefore, it becomes a technical problem to utilize the structure of the electronic device for implementing the function of transmitting and receiving multi-frequency band signals by an antenna.